jtag: cmsis-dap: developer tool - enter a command by hex nuber

[openocd.git] / src / jtag / drivers / cmsis_dap_usb.c

/***************************************************************************
 *   Copyright (C) 2016 by Maksym Hilliaka                                 *
 *   oter@frozen-team.com                                                  *
 *                                                                         *
 *   Copyright (C) 2016 by Phillip Pearson                                 *
 *   pp@myelin.co.nz                                                       *
 *                                                                         *
 *   Copyright (C) 2014 by Paul Fertser                                    *
 *   fercerpav@gmail.com                                                   *
 *                                                                         *
 *   Copyright (C) 2013 by mike brown                                      *
 *   mike@theshedworks.org.uk                                              *
 *                                                                         *
 *   Copyright (C) 2013 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <transport/transport.h>
#include <jtag/swd.h>
#include <jtag/interface.h>
#include <jtag/commands.h>
#include <jtag/tcl.h>

#include <hidapi.h>

/*
 * See CMSIS-DAP documentation:
 * Version 0.01 - Beta.
 */

/* USB Config */

/* Known vid/pid pairs:
 * VID 0xc251: Keil Software
 * PID 0xf001: LPC-Link-II CMSIS_DAP
 * PID 0xf002: OPEN-SDA CMSIS_DAP (Freedom Board)
 * PID 0x2722: Keil ULINK2 CMSIS-DAP
 *
 * VID 0x0d28: mbed Software
 * PID 0x0204: MBED CMSIS-DAP
 */

#define MAX_USB_IDS 8
/* vid = pid = 0 marks the end of the list */
static uint16_t cmsis_dap_vid[MAX_USB_IDS + 1] = { 0 };
static uint16_t cmsis_dap_pid[MAX_USB_IDS + 1] = { 0 };
static wchar_t *cmsis_dap_serial;
static bool swd_mode;

#define PACKET_SIZE       (64 + 1)      /* 64 bytes plus report id */
#define USB_TIMEOUT       1000

/* CMSIS-DAP General Commands */
#define CMD_DAP_INFO              0x00
#define CMD_DAP_LED               0x01
#define CMD_DAP_CONNECT           0x02
#define CMD_DAP_DISCONNECT        0x03
#define CMD_DAP_WRITE_ABORT       0x08
#define CMD_DAP_DELAY             0x09
#define CMD_DAP_RESET_TARGET      0x0A

/* CMD_INFO */
#define INFO_ID_VID               0x00      /* string */
#define INFO_ID_PID               0x02      /* string */
#define INFO_ID_SERNUM            0x03      /* string */
#define INFO_ID_FW_VER            0x04      /* string */
#define INFO_ID_TD_VEND           0x05      /* string */
#define INFO_ID_TD_NAME           0x06      /* string */
#define INFO_ID_CAPS              0xf0      /* byte */
#define INFO_ID_PKT_CNT           0xfe      /* byte */
#define INFO_ID_PKT_SZ            0xff      /* short */

#define INFO_CAPS_SWD             0x01
#define INFO_CAPS_JTAG            0x02

/* CMD_LED */
#define LED_ID_CONNECT            0x00
#define LED_ID_RUN                0x01

#define LED_OFF                   0x00
#define LED_ON                    0x01

/* CMD_CONNECT */
#define CONNECT_DEFAULT           0x00
#define CONNECT_SWD               0x01
#define CONNECT_JTAG              0x02

/* CMSIS-DAP Common SWD/JTAG Commands */
#define CMD_DAP_DELAY             0x09
#define CMD_DAP_SWJ_PINS          0x10
#define CMD_DAP_SWJ_CLOCK         0x11
#define CMD_DAP_SWJ_SEQ           0x12

/*
 * PINS
 * Bit 0: SWCLK/TCK
 * Bit 1: SWDIO/TMS
 * Bit 2: TDI
 * Bit 3: TDO
 * Bit 5: nTRST
 * Bit 7: nRESET
 */

#define SWJ_PIN_TCK               (1<<0)
#define SWJ_PIN_TMS               (1<<1)
#define SWJ_PIN_TDI               (1<<2)
#define SWJ_PIN_TDO               (1<<3)
#define SWJ_PIN_TRST              (1<<5)
#define SWJ_PIN_SRST              (1<<7)

/* CMSIS-DAP SWD Commands */
#define CMD_DAP_SWD_CONFIGURE     0x13

/* CMSIS-DAP JTAG Commands */
#define CMD_DAP_JTAG_SEQ          0x14
#define CMD_DAP_JTAG_CONFIGURE    0x15
#define CMD_DAP_JTAG_IDCODE       0x16

/* CMSIS-DAP JTAG sequence info masks */
/* Number of bits to clock through (0 means 64) */
#define DAP_JTAG_SEQ_TCK          0x3F
/* TMS will be set during the sequence if this bit is set */
#define DAP_JTAG_SEQ_TMS          0x40
/* TDO output will be captured if this bit is set */
#define DAP_JTAG_SEQ_TDO          0x80


/* CMSIS-DAP Transfer Commands */
#define CMD_DAP_TFER_CONFIGURE    0x04
#define CMD_DAP_TFER              0x05
#define CMD_DAP_TFER_BLOCK        0x06
#define CMD_DAP_TFER_ABORT        0x07

/* DAP Status Code */
#define DAP_OK                    0
#define DAP_ERROR                 0xFF

/* CMSIS-DAP Vendor Commands
 * None as yet... */

static const char * const info_caps_str[] = {
        "SWD  Supported",
        "JTAG Supported"
};

/* max clock speed (kHz) */
#define DAP_MAX_CLOCK             5000

struct cmsis_dap {
        hid_device *dev_handle;
        uint16_t packet_size;
        int packet_count;
        uint8_t *packet_buffer;
        uint8_t caps;
        uint8_t mode;
};

struct pending_transfer_result {
        uint8_t cmd;
        uint32_t data;
        void *buffer;
};

struct pending_request_block {
        struct pending_transfer_result *transfers;
        int transfer_count;
};

struct pending_scan_result {
        /** Offset in bytes in the CMD_DAP_JTAG_SEQ response buffer. */
        unsigned first;
        /** Number of bits to read. */
        unsigned length;
        /** Location to store the result */
        uint8_t *buffer;
        /** Offset in the destination buffer */
        unsigned buffer_offset;
};

/* Up to MIN(packet_count, MAX_PENDING_REQUESTS) requests may be issued
 * until the first response arrives */
#define MAX_PENDING_REQUESTS 3

/* Pending requests are organized as a FIFO - circular buffer */
/* Each block in FIFO can contain up to pending_queue_len transfers */
static int pending_queue_len;
static struct pending_request_block pending_fifo[MAX_PENDING_REQUESTS];
static int pending_fifo_put_idx, pending_fifo_get_idx;
static int pending_fifo_block_count;

/* pointers to buffers that will receive jtag scan results on the next flush */
#define MAX_PENDING_SCAN_RESULTS 256
static int pending_scan_result_count;
static struct pending_scan_result pending_scan_results[MAX_PENDING_SCAN_RESULTS];

/* queued JTAG sequences that will be executed on the next flush */
#define QUEUED_SEQ_BUF_LEN (cmsis_dap_handle->packet_size - 3)
static int queued_seq_count;
static int queued_seq_buf_end;
static int queued_seq_tdo_ptr;
static uint8_t queued_seq_buf[1024]; /* TODO: make dynamic / move into cmsis object */

static int queued_retval;

static uint8_t output_pins = SWJ_PIN_SRST | SWJ_PIN_TRST;

static struct cmsis_dap *cmsis_dap_handle;

static int cmsis_dap_usb_open(void)
{
        hid_device *dev = NULL;
        int i;
        struct hid_device_info *devs, *cur_dev;
        unsigned short target_vid, target_pid;
        wchar_t *target_serial = NULL;

        bool found = false;
        bool serial_found = false;

        target_vid = 0;
        target_pid = 0;

        /*
         * The CMSIS-DAP specification stipulates:
         * "The Product String must contain "CMSIS-DAP" somewhere in the string. This is used by the
         * debuggers to identify a CMSIS-DAP compliant Debug Unit that is connected to a host computer."
         */
        devs = hid_enumerate(0x0, 0x0);
        cur_dev = devs;
        while (NULL != cur_dev) {
                if (0 == cmsis_dap_vid[0]) {
                        if (NULL == cur_dev->product_string) {
                                LOG_DEBUG("Cannot read product string of device 0x%x:0x%x",
                                          cur_dev->vendor_id, cur_dev->product_id);
                        } else {
                                if (wcsstr(cur_dev->product_string, L"CMSIS-DAP")) {
                                        /* if the user hasn't specified VID:PID *and*
                                         * product string contains "CMSIS-DAP", pick it
                                         */
                                        found = true;
                                }
                        }
                } else {
                        /* otherwise, exhaustively compare against all VID:PID in list */
                        for (i = 0; cmsis_dap_vid[i] || cmsis_dap_pid[i]; i++) {
                                if ((cmsis_dap_vid[i] == cur_dev->vendor_id) && (cmsis_dap_pid[i] == cur_dev->product_id))
                                        found = true;
                        }

                        if (cmsis_dap_vid[i] || cmsis_dap_pid[i])
                                found = true;
                }

                if (found) {
                        /* we have found an adapter, so exit further checks */
                        /* check serial number matches if given */
                        if (cmsis_dap_serial != NULL) {
                                if ((cur_dev->serial_number != NULL) && wcscmp(cmsis_dap_serial, cur_dev->serial_number) == 0) {
                                        serial_found = true;
                                        break;
                                }
                        } else
                                break;

                        found = false;
                }

                cur_dev = cur_dev->next;
        }

        if (NULL != cur_dev) {
                target_vid = cur_dev->vendor_id;
                target_pid = cur_dev->product_id;
                if (serial_found)
                        target_serial = cmsis_dap_serial;
        }

        hid_free_enumeration(devs);

        if (target_vid == 0 && target_pid == 0) {
                LOG_ERROR("unable to find CMSIS-DAP device");
                return ERROR_FAIL;
        }

        if (hid_init() != 0) {
                LOG_ERROR("unable to open HIDAPI");
                return ERROR_FAIL;
        }

        dev = hid_open(target_vid, target_pid, target_serial);

        if (dev == NULL) {
                LOG_ERROR("unable to open CMSIS-DAP device 0x%x:0x%x", target_vid, target_pid);
                return ERROR_FAIL;
        }

        struct cmsis_dap *dap = malloc(sizeof(struct cmsis_dap));
        if (dap == NULL) {
                LOG_ERROR("unable to allocate memory");
                return ERROR_FAIL;
        }

        dap->dev_handle = dev;
        dap->caps = 0;
        dap->mode = 0;

        cmsis_dap_handle = dap;

        /* allocate default packet buffer, may be changed later.
         * currently with HIDAPI we have no way of getting the output report length
         * without this info we cannot communicate with the adapter.
         * For the moment we ahve to hard code the packet size */

        int packet_size = PACKET_SIZE;

        /* atmel cmsis-dap uses 512 byte reports */
        /* except when it doesn't e.g. with mEDBG on SAMD10 Xplained
         * board */
        /* TODO: HID report descriptor should be parsed instead of
         * hardcoding a match by VID */
        if (target_vid == 0x03eb && target_pid != 0x2145)
                packet_size = 512 + 1;

        cmsis_dap_handle->packet_buffer = malloc(packet_size);
        cmsis_dap_handle->packet_size = packet_size;

        if (cmsis_dap_handle->packet_buffer == NULL) {
                LOG_ERROR("unable to allocate memory");
                return ERROR_FAIL;
        }

        return ERROR_OK;
}

static void cmsis_dap_usb_close(struct cmsis_dap *dap)
{
        hid_close(dap->dev_handle);
        hid_exit();

        free(cmsis_dap_handle->packet_buffer);
        free(cmsis_dap_handle);
        cmsis_dap_handle = NULL;
        free(cmsis_dap_serial);
        cmsis_dap_serial = NULL;

        for (int i = 0; i < MAX_PENDING_REQUESTS; i++) {
                free(pending_fifo[i].transfers);
                pending_fifo[i].transfers = NULL;
        }

        return;
}

static int cmsis_dap_usb_write(struct cmsis_dap *dap, int txlen)
{
#ifdef CMSIS_DAP_JTAG_DEBUG
        LOG_DEBUG("cmsis-dap usb xfer cmd=%02X", dap->packet_buffer[1]);
#endif
        /* Pad the rest of the TX buffer with 0's */
        memset(dap->packet_buffer + txlen, 0, dap->packet_size - txlen);

        /* write data to device */
        int retval = hid_write(dap->dev_handle, dap->packet_buffer, dap->packet_size);
        if (retval == -1) {
                LOG_ERROR("error writing data: %ls", hid_error(dap->dev_handle));
                return ERROR_FAIL;
        }

        return ERROR_OK;
}

/* Send a message and receive the reply */
static int cmsis_dap_usb_xfer(struct cmsis_dap *dap, int txlen)
{
        if (pending_fifo_block_count) {
                LOG_ERROR("pending %d blocks, flushing", pending_fifo_block_count);
                while (pending_fifo_block_count) {
                        hid_read_timeout(dap->dev_handle, dap->packet_buffer, dap->packet_size, 10);
                        pending_fifo_block_count--;
                }
                pending_fifo_put_idx = 0;
                pending_fifo_get_idx = 0;
        }

        int retval = cmsis_dap_usb_write(dap, txlen);
        if (retval != ERROR_OK)
                return retval;

        /* get reply */
        retval = hid_read_timeout(dap->dev_handle, dap->packet_buffer, dap->packet_size, USB_TIMEOUT);
        if (retval == -1 || retval == 0) {
                LOG_DEBUG("error reading data: %ls", hid_error(dap->dev_handle));
                return ERROR_FAIL;
        }

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWJ_Pins(uint8_t pins, uint8_t mask, uint32_t delay, uint8_t *input)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_SWJ_PINS;
        buffer[2] = pins;
        buffer[3] = mask;
        buffer[4] = delay & 0xff;
        buffer[5] = (delay >> 8) & 0xff;
        buffer[6] = (delay >> 16) & 0xff;
        buffer[7] = (delay >> 24) & 0xff;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 8);

        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DAP_SWJ_PINS failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (input)
                *input = buffer[1];

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWJ_Clock(uint32_t swj_clock)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        /* set clock in Hz */
        swj_clock *= 1000;
        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_SWJ_CLOCK;
        buffer[2] = swj_clock & 0xff;
        buffer[3] = (swj_clock >> 8) & 0xff;
        buffer[4] = (swj_clock >> 16) & 0xff;
        buffer[5] = (swj_clock >> 24) & 0xff;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 6);

        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DAP_SWJ_CLOCK failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

/* clock a sequence of bits out on TMS, to change JTAG states */
static int cmsis_dap_cmd_DAP_SWJ_Sequence(uint8_t s_len, const uint8_t *sequence)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

#ifdef CMSIS_DAP_JTAG_DEBUG
        LOG_DEBUG("cmsis-dap TMS sequence: len=%d", s_len);
        for (int i = 0; i < DIV_ROUND_UP(s_len, 8); ++i)
                printf("%02X ", sequence[i]);

        printf("\n");
#endif

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_SWJ_SEQ;
        buffer[2] = s_len;
        bit_copy(&buffer[3], 0, sequence, 0, s_len);

        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, DIV_ROUND_UP(s_len, 8) + 3);

        if (retval != ERROR_OK || buffer[1] != DAP_OK)
                return ERROR_FAIL;

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Info(uint8_t info, uint8_t **data)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_INFO;
        buffer[2] = info;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_INFO failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        *data = &(buffer[1]);

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_LED(uint8_t leds)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_LED;
        buffer[2] = 0x00;
        buffer[3] = leds;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 4);

        if (retval != ERROR_OK || buffer[1] != 0x00) {
                LOG_ERROR("CMSIS-DAP command CMD_LED failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Connect(uint8_t mode)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_CONNECT;
        buffer[2] = mode;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_CONNECT failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        if (buffer[1] != mode) {
                LOG_ERROR("CMSIS-DAP failed to connect in mode (%d)", mode);
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_Disconnect(void)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_DISCONNECT;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 2);

        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DISCONNECT failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_TFER_Configure(uint8_t idle, uint16_t retry_count, uint16_t match_retry)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_TFER_CONFIGURE;
        buffer[2] = idle;
        buffer[3] = retry_count & 0xff;
        buffer[4] = (retry_count >> 8) & 0xff;
        buffer[5] = match_retry & 0xff;
        buffer[6] = (match_retry >> 8) & 0xff;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 7);

        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_TFER_Configure failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

static int cmsis_dap_cmd_DAP_SWD_Configure(uint8_t cfg)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_SWD_CONFIGURE;
        buffer[2] = cfg;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 3);

        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_SWD_Configure failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}

#if 0
static int cmsis_dap_cmd_DAP_Delay(uint16_t delay_us)
{
        int retval;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_DELAY;
        buffer[2] = delay_us & 0xff;
        buffer[3] = (delay_us >> 8) & 0xff;
        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, 4);

        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_Delay failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        return ERROR_OK;
}
#endif

static void cmsis_dap_swd_write_from_queue(struct cmsis_dap *dap)
{
        uint8_t *buffer = dap->packet_buffer;
        struct pending_request_block *block = &pending_fifo[pending_fifo_put_idx];

        LOG_DEBUG_IO("Executing %d queued transactions from FIFO index %d", block->transfer_count, pending_fifo_put_idx);

        if (queued_retval != ERROR_OK) {
                LOG_DEBUG("Skipping due to previous errors: %d", queued_retval);
                goto skip;
        }

        if (block->transfer_count == 0)
                goto skip;

        size_t idx = 0;
        buffer[idx++] = 0;      /* report number */
        buffer[idx++] = CMD_DAP_TFER;
        buffer[idx++] = 0x00;   /* DAP Index */
        buffer[idx++] = block->transfer_count;

        for (int i = 0; i < block->transfer_count; i++) {
                struct pending_transfer_result *transfer = &(block->transfers[i]);
                uint8_t cmd = transfer->cmd;
                uint32_t data = transfer->data;

                LOG_DEBUG_IO("%s %s reg %x %"PRIx32,
                                cmd & SWD_CMD_APnDP ? "AP" : "DP",
                                cmd & SWD_CMD_RnW ? "read" : "write",
                          (cmd & SWD_CMD_A32) >> 1, data);

                /* When proper WAIT handling is implemented in the
                 * common SWD framework, this kludge can be
                 * removed. However, this might lead to minor
                 * performance degradation as the adapter wouldn't be
                 * able to automatically retry anything (because ARM
                 * has forgotten to implement sticky error flags
                 * clearing). See also comments regarding
                 * cmsis_dap_cmd_DAP_TFER_Configure() and
                 * cmsis_dap_cmd_DAP_SWD_Configure() in
                 * cmsis_dap_init().
                 */
                if (!(cmd & SWD_CMD_RnW) &&
                    !(cmd & SWD_CMD_APnDP) &&
                    (cmd & SWD_CMD_A32) >> 1 == DP_CTRL_STAT &&
                    (data & CORUNDETECT)) {
                        LOG_DEBUG("refusing to enable sticky overrun detection");
                        data &= ~CORUNDETECT;
                }

                buffer[idx++] = (cmd >> 1) & 0x0f;
                if (!(cmd & SWD_CMD_RnW)) {
                        buffer[idx++] = (data) & 0xff;
                        buffer[idx++] = (data >> 8) & 0xff;
                        buffer[idx++] = (data >> 16) & 0xff;
                        buffer[idx++] = (data >> 24) & 0xff;
                }
        }

        queued_retval = cmsis_dap_usb_write(dap, idx);
        if (queued_retval != ERROR_OK)
                goto skip;

        pending_fifo_put_idx = (pending_fifo_put_idx + 1) % dap->packet_count;
        pending_fifo_block_count++;
        if (pending_fifo_block_count > dap->packet_count)
                LOG_ERROR("too much pending writes %d", pending_fifo_block_count);

        return;

skip:
        block->transfer_count = 0;
}

static void cmsis_dap_swd_read_process(struct cmsis_dap *dap, int timeout_ms)
{
        uint8_t *buffer = dap->packet_buffer;
        struct pending_request_block *block = &pending_fifo[pending_fifo_get_idx];

        if (pending_fifo_block_count == 0)
                LOG_ERROR("no pending write");

        /* get reply */
        int retval = hid_read_timeout(dap->dev_handle, dap->packet_buffer, dap->packet_size, timeout_ms);
        if (retval == 0 && timeout_ms < USB_TIMEOUT)
                return;

        if (retval == -1 || retval == 0) {
                LOG_DEBUG("error reading data: %ls", hid_error(dap->dev_handle));
                queued_retval = ERROR_FAIL;
                goto skip;
        }

        if (buffer[2] & 0x08) {
                LOG_DEBUG("CMSIS-DAP Protocol Error @ %d (wrong parity)", buffer[1]);
                queued_retval = ERROR_FAIL;
                goto skip;
        }
        uint8_t ack = buffer[2] & 0x07;
        if (ack != SWD_ACK_OK) {
                LOG_DEBUG("SWD ack not OK @ %d %s", buffer[1],
                          ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK");
                queued_retval = ack == SWD_ACK_WAIT ? ERROR_WAIT : ERROR_FAIL;
                goto skip;
        }

        if (block->transfer_count != buffer[1])
                LOG_ERROR("CMSIS-DAP transfer count mismatch: expected %d, got %d",
                          block->transfer_count, buffer[1]);

        LOG_DEBUG_IO("Received results of %d queued transactions FIFO index %d", buffer[1], pending_fifo_get_idx);
        size_t idx = 3;
        for (int i = 0; i < buffer[1]; i++) {
                struct pending_transfer_result *transfer = &(block->transfers[i]);
                if (transfer->cmd & SWD_CMD_RnW) {
                        static uint32_t last_read;
                        uint32_t data = le_to_h_u32(&buffer[idx]);
                        uint32_t tmp = data;
                        idx += 4;

                        LOG_DEBUG_IO("Read result: %"PRIx32, data);

                        /* Imitate posted AP reads */
                        if ((transfer->cmd & SWD_CMD_APnDP) ||
                            ((transfer->cmd & SWD_CMD_A32) >> 1 == DP_RDBUFF)) {
                                tmp = last_read;
                                last_read = data;
                        }

                        if (transfer->buffer)
                                *(uint32_t *)(transfer->buffer) = tmp;
                }
        }

skip:
        block->transfer_count = 0;
        pending_fifo_get_idx = (pending_fifo_get_idx + 1) % dap->packet_count;
        pending_fifo_block_count--;
}

static int cmsis_dap_swd_run_queue(void)
{
        if (pending_fifo_block_count)
                cmsis_dap_swd_read_process(cmsis_dap_handle, 0);

        cmsis_dap_swd_write_from_queue(cmsis_dap_handle);

        while (pending_fifo_block_count)
                cmsis_dap_swd_read_process(cmsis_dap_handle, USB_TIMEOUT);

        pending_fifo_put_idx = 0;
        pending_fifo_get_idx = 0;

        int retval = queued_retval;
        queued_retval = ERROR_OK;

        return retval;
}

static void cmsis_dap_swd_queue_cmd(uint8_t cmd, uint32_t *dst, uint32_t data)
{
        if (pending_fifo[pending_fifo_put_idx].transfer_count == pending_queue_len) {
                if (pending_fifo_block_count)
                        cmsis_dap_swd_read_process(cmsis_dap_handle, 0);

                /* Not enough room in the queue. Run the queue. */
                cmsis_dap_swd_write_from_queue(cmsis_dap_handle);

                if (pending_fifo_block_count >= cmsis_dap_handle->packet_count)
                        cmsis_dap_swd_read_process(cmsis_dap_handle, USB_TIMEOUT);
        }

        if (queued_retval != ERROR_OK)
                return;

        struct pending_request_block *block = &pending_fifo[pending_fifo_put_idx];
        struct pending_transfer_result *transfer = &(block->transfers[block->transfer_count]);
        transfer->data = data;
        transfer->cmd = cmd;
        if (cmd & SWD_CMD_RnW) {
                /* Queue a read transaction */
                transfer->buffer = dst;
        }
        block->transfer_count++;
}

static void cmsis_dap_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
{
        assert(!(cmd & SWD_CMD_RnW));
        cmsis_dap_swd_queue_cmd(cmd, NULL, value);
}

static void cmsis_dap_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
{
        assert(cmd & SWD_CMD_RnW);
        cmsis_dap_swd_queue_cmd(cmd, value, 0);
}

static int cmsis_dap_get_serial_info(void)
{
        uint8_t *data;

        int retval = cmsis_dap_cmd_DAP_Info(INFO_ID_SERNUM, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0]) /* strlen */
                LOG_INFO("CMSIS-DAP: Serial# = %s", &data[1]);

        return ERROR_OK;
}

static int cmsis_dap_get_version_info(void)
{
        uint8_t *data;

        /* INFO_ID_FW_VER - string */
        int retval = cmsis_dap_cmd_DAP_Info(INFO_ID_FW_VER, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0]) /* strlen */
                LOG_INFO("CMSIS-DAP: FW Version = %s", &data[1]);

        return ERROR_OK;
}

static int cmsis_dap_get_caps_info(void)
{
        uint8_t *data;

        /* INFO_ID_CAPS - byte */
        int retval = cmsis_dap_cmd_DAP_Info(INFO_ID_CAPS, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0] == 1) {
                uint8_t caps = data[1];

                cmsis_dap_handle->caps = caps;

                if (caps & INFO_CAPS_SWD)
                        LOG_INFO("CMSIS-DAP: %s", info_caps_str[0]);
                if (caps & INFO_CAPS_JTAG)
                        LOG_INFO("CMSIS-DAP: %s", info_caps_str[1]);
        }

        return ERROR_OK;
}

static int cmsis_dap_get_status(void)
{
        uint8_t d;

        int retval = cmsis_dap_cmd_DAP_SWJ_Pins(0, 0, 0, &d);

        if (retval == ERROR_OK) {
                LOG_INFO("SWCLK/TCK = %d SWDIO/TMS = %d TDI = %d TDO = %d nTRST = %d nRESET = %d",
                        (d & SWJ_PIN_TCK) ? 1 : 0,
                        (d & SWJ_PIN_TMS) ? 1 : 0,
                        (d & SWJ_PIN_TDI) ? 1 : 0,
                        (d & SWJ_PIN_TDO) ? 1 : 0,
                        (d & SWJ_PIN_TRST) ? 1 : 0,
                        (d & SWJ_PIN_SRST) ? 1 : 0);
        }

        return retval;
}

static int cmsis_dap_swd_switch_seq(enum swd_special_seq seq)
{
        const uint8_t *s;
        unsigned int s_len;
        int retval;

        if ((output_pins & (SWJ_PIN_SRST | SWJ_PIN_TRST)) == (SWJ_PIN_SRST | SWJ_PIN_TRST)) {
                /* Following workaround deasserts reset on most adapters.
                 * Do not reconnect if a reset line is active!
                 * Reconnecting would break connecting under reset. */

                /* First disconnect before connecting, Atmel EDBG needs it for SAMD/R/L/C */
                cmsis_dap_cmd_DAP_Disconnect();

                /* When we are reconnecting, DAP_Connect needs to be rerun, at
                 * least on Keil ULINK-ME */
                retval = cmsis_dap_cmd_DAP_Connect(CONNECT_SWD);
                if (retval != ERROR_OK)
                        return retval;
        }

        switch (seq) {
        case LINE_RESET:
                LOG_DEBUG("SWD line reset");
                s = swd_seq_line_reset;
                s_len = swd_seq_line_reset_len;
                break;
        case JTAG_TO_SWD:
                LOG_DEBUG("JTAG-to-SWD");
                s = swd_seq_jtag_to_swd;
                s_len = swd_seq_jtag_to_swd_len;
                break;
        case SWD_TO_JTAG:
                LOG_DEBUG("SWD-to-JTAG");
                s = swd_seq_swd_to_jtag;
                s_len = swd_seq_swd_to_jtag_len;
                break;
        default:
                LOG_ERROR("Sequence %d not supported", seq);
                return ERROR_FAIL;
        }

        retval = cmsis_dap_cmd_DAP_SWJ_Sequence(s_len, s);
        if (retval != ERROR_OK)
                return retval;

        /* Atmel EDBG needs renew clock setting after SWJ_Sequence
         * otherwise default frequency is used */
        return cmsis_dap_cmd_DAP_SWJ_Clock(jtag_get_speed_khz());
}

static int cmsis_dap_swd_open(void)
{
        int retval;

        if (!(cmsis_dap_handle->caps & INFO_CAPS_SWD)) {
                LOG_ERROR("CMSIS-DAP: SWD not supported");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        retval = cmsis_dap_cmd_DAP_Connect(CONNECT_SWD);
        if (retval != ERROR_OK)
                return retval;

        /* Add more setup here.??... */

        LOG_INFO("CMSIS-DAP: Interface Initialised (SWD)");
        return ERROR_OK;
}

static int cmsis_dap_init(void)
{
        int retval;
        uint8_t *data;

        retval = cmsis_dap_usb_open();
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_get_caps_info();
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_get_version_info();
        if (retval != ERROR_OK)
                return retval;

        retval = cmsis_dap_get_serial_info();
        if (retval != ERROR_OK)
                return retval;

        if (swd_mode) {
                retval = cmsis_dap_swd_open();
                if (retval != ERROR_OK)
                        return retval;
        } else {
                /* Connect in JTAG mode */
                if (!(cmsis_dap_handle->caps & INFO_CAPS_JTAG)) {
                        LOG_ERROR("CMSIS-DAP: JTAG not supported");
                        return ERROR_JTAG_DEVICE_ERROR;
                }

                retval = cmsis_dap_cmd_DAP_Connect(CONNECT_JTAG);
                if (retval != ERROR_OK)
                        return retval;

                LOG_INFO("CMSIS-DAP: Interface Initialised (JTAG)");
        }

        /* Be conservative and supress submiting multiple HID requests
         * until we get packet count info from the adaptor */
        cmsis_dap_handle->packet_count = 1;
        pending_queue_len = 12;

        /* INFO_ID_PKT_SZ - short */
        retval = cmsis_dap_cmd_DAP_Info(INFO_ID_PKT_SZ, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0] == 2) {  /* short */
                uint16_t pkt_sz = data[1] + (data[2] << 8);

                /* 4 bytes of command header + 5 bytes per register
                 * write. For bulk read sequences just 4 bytes are
                 * needed per transfer, so this is suboptimal. */
                pending_queue_len = (pkt_sz - 4) / 5;

                if (cmsis_dap_handle->packet_size != pkt_sz + 1) {
                        /* reallocate buffer */
                        cmsis_dap_handle->packet_size = pkt_sz + 1;
                        cmsis_dap_handle->packet_buffer = realloc(cmsis_dap_handle->packet_buffer,
                                        cmsis_dap_handle->packet_size);
                        if (cmsis_dap_handle->packet_buffer == NULL) {
                                LOG_ERROR("unable to reallocate memory");
                                return ERROR_FAIL;
                        }
                }

                LOG_DEBUG("CMSIS-DAP: Packet Size = %" PRId16, pkt_sz);
        }

        /* INFO_ID_PKT_CNT - byte */
        retval = cmsis_dap_cmd_DAP_Info(INFO_ID_PKT_CNT, &data);
        if (retval != ERROR_OK)
                return retval;

        if (data[0] == 1) { /* byte */
                int pkt_cnt = data[1];
                if (pkt_cnt > 1)
                        cmsis_dap_handle->packet_count = MIN(MAX_PENDING_REQUESTS, pkt_cnt);

                LOG_DEBUG("CMSIS-DAP: Packet Count = %d", pkt_cnt);
        }

        LOG_DEBUG("Allocating FIFO for %d pending HID requests", cmsis_dap_handle->packet_count);
        for (int i = 0; i < cmsis_dap_handle->packet_count; i++) {
                pending_fifo[i].transfers = malloc(pending_queue_len * sizeof(struct pending_transfer_result));
                if (!pending_fifo[i].transfers) {
                        LOG_ERROR("Unable to allocate memory for CMSIS-DAP queue");
                        return ERROR_FAIL;
                }
        }


        retval = cmsis_dap_get_status();
        if (retval != ERROR_OK)
                return ERROR_FAIL;

        /* Now try to connect to the target
         * TODO: This is all SWD only @ present */
        retval = cmsis_dap_cmd_DAP_SWJ_Clock(jtag_get_speed_khz());
        if (retval != ERROR_OK)
                return ERROR_FAIL;

        /* Ask CMSIS-DAP to automatically retry on receiving WAIT for
         * up to 64 times. This must be changed to 0 if sticky
         * overrun detection is enabled. */
        retval = cmsis_dap_cmd_DAP_TFER_Configure(0, 64, 0);
        if (retval != ERROR_OK)
                return ERROR_FAIL;

        if (swd_mode) {
                /* Data Phase (bit 2) must be set to 1 if sticky overrun
                 * detection is enabled */
                retval = cmsis_dap_cmd_DAP_SWD_Configure(0);    /* 1 TRN, no Data Phase */
                if (retval != ERROR_OK)
                        return ERROR_FAIL;
        }

        retval = cmsis_dap_cmd_DAP_LED(0x03);           /* Both LEDs on */
        if (retval != ERROR_OK)
                return ERROR_FAIL;

        /* support connecting with srst asserted */
        enum reset_types jtag_reset_config = jtag_get_reset_config();

        if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
                if (jtag_reset_config & RESET_SRST_NO_GATING) {
                        retval = cmsis_dap_cmd_DAP_SWJ_Pins(0, (1 << 7), 0, NULL);
                        if (retval != ERROR_OK)
                                return ERROR_FAIL;
                        LOG_INFO("Connecting under reset");
                }
        }

        cmsis_dap_cmd_DAP_LED(0x00);                    /* Both LEDs off */

        LOG_INFO("CMSIS-DAP: Interface ready");

        return ERROR_OK;
}

static int cmsis_dap_swd_init(void)
{
        swd_mode = true;
        return ERROR_OK;
}

static int cmsis_dap_quit(void)
{
        cmsis_dap_cmd_DAP_Disconnect();
        cmsis_dap_cmd_DAP_LED(0x00);            /* Both LEDs off */

        cmsis_dap_usb_close(cmsis_dap_handle);

        return ERROR_OK;
}

static void cmsis_dap_execute_reset(struct jtag_command *cmd)
{
        /* Set both TRST and SRST even if they're not enabled as
         * there's no way to tristate them */

        output_pins = 0;
        if (!cmd->cmd.reset->srst)
                output_pins |= SWJ_PIN_SRST;
        if (!cmd->cmd.reset->trst)
                output_pins |= SWJ_PIN_TRST;

        int retval = cmsis_dap_cmd_DAP_SWJ_Pins(output_pins,
                        SWJ_PIN_TRST | SWJ_PIN_SRST, 0, NULL);
        if (retval != ERROR_OK)
                LOG_ERROR("CMSIS-DAP: Interface reset failed");
}

static void cmsis_dap_execute_sleep(struct jtag_command *cmd)
{
#if 0
        int retval = cmsis_dap_cmd_DAP_Delay(cmd->cmd.sleep->us);
        if (retval != ERROR_OK)
#endif
                jtag_sleep(cmd->cmd.sleep->us);
}

/* Set TMS high for five TCK clocks, to move the TAP to the Test-Logic-Reset state */
static int cmsis_dap_execute_tlr_reset(struct jtag_command *cmd)
{
        LOG_INFO("cmsis-dap JTAG TLR_RESET");
        uint8_t seq = 0xff;
        int ret = cmsis_dap_cmd_DAP_SWJ_Sequence(8, &seq);
        if (ret == ERROR_OK)
                tap_set_state(TAP_RESET);
        return ret;
}

/* Set new end state */
static void cmsis_dap_end_state(tap_state_t state)
{
        if (tap_is_state_stable(state))
                tap_set_end_state(state);
        else {
                LOG_ERROR("BUG: %i is not a valid end state", state);
                exit(-1);
        }
}

#ifdef SPRINT_BINARY
static void sprint_binary(char *s, const uint8_t *buf, int offset, int len)
{
        if (!len)
                return;

        /*
        buf = { 0x18 } len=5 should result in: 11000
        buf = { 0xff 0x18 } len=13 should result in: 11111111 11000
        buf = { 0xc0 0x18 } offset=3 len=10 should result in: 11000 11000
                i=3 there means i/8 = 0 so c = 0xFF, and
        */
        for (int i = offset; i < offset + len; ++i) {
                uint8_t c = buf[i / 8], mask = 1 << (i % 8);
                if ((i != offset) && !(i % 8))
                        putchar(' ');
                *s++ = (c & mask) ? '1' : '0';
        }
        *s = 0;
}
#endif

#ifdef CMSIS_DAP_JTAG_DEBUG
static void debug_parse_cmsis_buf(const uint8_t *cmd, int cmdlen)
{
        /* cmd is a usb packet to go to the cmsis-dap interface */
        printf("cmsis-dap buffer (%d b): ", cmdlen);
        for (int i = 0; i < cmdlen; ++i)
                printf(" %02x", cmd[i]);
        printf("\n");
        switch (cmd[1]) {
                case CMD_DAP_JTAG_SEQ: {
                        printf("cmsis-dap jtag sequence command %02x (n=%d)\n", cmd[1], cmd[2]);
                        /*
                         * #2 = number of sequences
                         * #3 = sequence info 1
                         * #4...4+n_bytes-1 = sequence 1
                         * #4+n_bytes = sequence info 2
                         * #5+n_bytes = sequence 2 (single bit)
                         */
                        int pos = 3;
                        for (int seq = 0; seq < cmd[2]; ++seq) {
                                uint8_t info = cmd[pos++];
                                int len = info & DAP_JTAG_SEQ_TCK;
                                if (len == 0)
                                        len = 64;
                                printf("  sequence %d starting %d: info %02x (len=%d tms=%d read_tdo=%d): ",
                                        seq, pos, info, len, info & DAP_JTAG_SEQ_TMS, info & DAP_JTAG_SEQ_TDO);
                                for (int i = 0; i < DIV_ROUND_UP(len, 8); ++i)
                                        printf(" %02x", cmd[pos+i]);
                                pos += DIV_ROUND_UP(len, 8);
                                printf("\n");
                        }
                        if (pos != cmdlen) {
                                printf("BUFFER LENGTH MISMATCH looks like %d but %d specified", pos, cmdlen);
                                exit(-1);
                        }

                        break;
                }
                default:
                        LOG_DEBUG("unknown cmsis-dap command %02x", cmd[1]);
                        break;
        }
}
#endif

static void cmsis_dap_flush(void)
{
        if (!queued_seq_count)
                return;

        DEBUG_JTAG_IO("Flushing %d queued sequences (%d bytes) with %d pending scan results to capture",
                queued_seq_count, queued_seq_buf_end, pending_scan_result_count);

        /* prep CMSIS-DAP packet */
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;
        buffer[0] = 0;  /* report number */
        buffer[1] = CMD_DAP_JTAG_SEQ;
        buffer[2] = queued_seq_count;
        memcpy(buffer + 3, queued_seq_buf, queued_seq_buf_end);

#ifdef CMSIS_DAP_JTAG_DEBUG
        debug_parse_cmsis_buf(buffer, queued_seq_buf_end + 3);
#endif

        /* send command to USB device */
        int retval = cmsis_dap_usb_xfer(cmsis_dap_handle, queued_seq_buf_end + 3);
        if (retval != ERROR_OK || buffer[1] != DAP_OK) {
                LOG_ERROR("CMSIS-DAP command CMD_DAP_JTAG_SEQ failed.");
                exit(-1);
        }

#ifdef CMSIS_DAP_JTAG_DEBUG
        DEBUG_JTAG_IO("USB response buf:");
        for (int c = 0; c < queued_seq_buf_end + 3; ++c)
                printf("%02X ", buffer[c]);
        printf("\n");
#endif

        /* copy scan results into client buffers */
        for (int i = 0; i < pending_scan_result_count; ++i) {
                struct pending_scan_result *scan = &pending_scan_results[i];
                DEBUG_JTAG_IO("Copying pending_scan_result %d/%d: %d bits from byte %d -> buffer + %d bits",
                        i, pending_scan_result_count, scan->length, scan->first + 2, scan->buffer_offset);
#ifdef CMSIS_DAP_JTAG_DEBUG
                for (uint32_t b = 0; b < DIV_ROUND_UP(scan->length, 8); ++b)
                        printf("%02X ", buffer[2+scan->first+b]);
                printf("\n");
#endif
                bit_copy(scan->buffer, scan->buffer_offset, buffer + 2 + scan->first, 0, scan->length);
        }

        /* reset */
        queued_seq_count = 0;
        queued_seq_buf_end = 0;
        queued_seq_tdo_ptr = 0;
        pending_scan_result_count = 0;
}

/* queue a sequence of bits to clock out TDI / in TDO, executing if the buffer is full.
 *
 * sequence=NULL means clock out zeros on TDI
 * tdo_buffer=NULL means don't capture TDO
 */
static void cmsis_dap_add_jtag_sequence(int s_len, const uint8_t *sequence, int s_offset,
                                        bool tms, uint8_t *tdo_buffer, int tdo_buffer_offset)
{
        DEBUG_JTAG_IO("[at %d] %d bits, tms %s, seq offset %d, tdo buf %p, tdo offset %d",
                queued_seq_buf_end,
                s_len, tms ? "HIGH" : "LOW", s_offset, tdo_buffer, tdo_buffer_offset);

        if (s_len == 0)
                return;

        if (s_len > 64) {
                DEBUG_JTAG_IO("START JTAG SEQ SPLIT");
                for (int offset = 0; offset < s_len; offset += 64) {
                        int len = s_len - offset;
                        if (len > 64)
                                len = 64;
                        DEBUG_JTAG_IO("Splitting long jtag sequence: %d-bit chunk starting at offset %d", len, offset);
                        cmsis_dap_add_jtag_sequence(
                                len,
                                sequence,
                                s_offset + offset,
                                tms,
                                tdo_buffer,
                                tdo_buffer == NULL ? 0 : (tdo_buffer_offset + offset)
                                );
                }
                DEBUG_JTAG_IO("END JTAG SEQ SPLIT");
                return;
        }

        int cmd_len = 1 + DIV_ROUND_UP(s_len, 8);
        if (queued_seq_count >= 255 || queued_seq_buf_end + cmd_len > QUEUED_SEQ_BUF_LEN)
                /* empty out the buffer */
                cmsis_dap_flush();

        ++queued_seq_count;

        /* control byte */
        queued_seq_buf[queued_seq_buf_end] =
                (tms ? DAP_JTAG_SEQ_TMS : 0) |
                (tdo_buffer != NULL ? DAP_JTAG_SEQ_TDO : 0) |
                (s_len == 64 ? 0 : s_len);

        if (sequence != NULL)
                bit_copy(&queued_seq_buf[queued_seq_buf_end + 1], 0, sequence, s_offset, s_len);
        else
                memset(&queued_seq_buf[queued_seq_buf_end + 1], 0, DIV_ROUND_UP(s_len, 8));

        queued_seq_buf_end += cmd_len;

        if (tdo_buffer != NULL) {
                struct pending_scan_result *scan = &pending_scan_results[pending_scan_result_count++];
                scan->first = queued_seq_tdo_ptr;
                queued_seq_tdo_ptr += DIV_ROUND_UP(s_len, 8);
                scan->length = s_len;
                scan->buffer = tdo_buffer;
                scan->buffer_offset = tdo_buffer_offset;
        }
}

/* queue a sequence of bits to clock out TMS, executing if the buffer is full */
static void cmsis_dap_add_tms_sequence(const uint8_t *sequence, int s_len)
{
        DEBUG_JTAG_IO("%d bits: %02X", s_len, *sequence);
        /* we use a series of CMD_DAP_JTAG_SEQ commands to toggle TMS,
           because even though it seems ridiculously inefficient, it
           allows us to combine TMS and scan sequences into the same
           USB packet. */
        /* TODO: combine runs of the same tms value */
        for (int i = 0; i < s_len; ++i) {
                bool bit = (sequence[i / 8] & (1 << (i % 8))) != 0;
                cmsis_dap_add_jtag_sequence(1, NULL, 0, bit, NULL, 0);
        }
}

/* Move to the end state by queuing a sequence to clock into TMS */
static void cmsis_dap_state_move(void)
{
        uint8_t tms_scan;
        uint8_t tms_scan_bits;

        tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
        tms_scan_bits = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());

        DEBUG_JTAG_IO("state move from %s to %s: %d clocks, %02X on tms",
                tap_state_name(tap_get_state()), tap_state_name(tap_get_end_state()),
                tms_scan_bits, tms_scan);
        cmsis_dap_add_tms_sequence(&tms_scan, tms_scan_bits);

        tap_set_state(tap_get_end_state());
}


/* Execute a JTAG scan operation by queueing TMS and TDI/TDO sequences */
static void cmsis_dap_execute_scan(struct jtag_command *cmd)
{
        DEBUG_JTAG_IO("%s type:%d", cmd->cmd.scan->ir_scan ? "IRSCAN" : "DRSCAN",
                jtag_scan_type(cmd->cmd.scan));

        /* Make sure there are no trailing fields with num_bits == 0, or the logic below will fail. */
        while (cmd->cmd.scan->num_fields > 0
                        && cmd->cmd.scan->fields[cmd->cmd.scan->num_fields - 1].num_bits == 0) {
                cmd->cmd.scan->num_fields--;
                LOG_DEBUG("discarding trailing empty field");
        }

        if (cmd->cmd.scan->num_fields == 0) {
                LOG_DEBUG("empty scan, doing nothing");
                return;
        }

        if (cmd->cmd.scan->ir_scan) {
                if (tap_get_state() != TAP_IRSHIFT) {
                        cmsis_dap_end_state(TAP_IRSHIFT);
                        cmsis_dap_state_move();
                }
        } else {
                if (tap_get_state() != TAP_DRSHIFT) {
                        cmsis_dap_end_state(TAP_DRSHIFT);
                        cmsis_dap_state_move();
                }
        }

        cmsis_dap_end_state(cmd->cmd.scan->end_state);

        struct scan_field *field = cmd->cmd.scan->fields;
        unsigned scan_size = 0;

        for (int i = 0; i < cmd->cmd.scan->num_fields; i++, field++) {
                scan_size += field->num_bits;
                DEBUG_JTAG_IO("%s%s field %d/%d %d bits",
                        field->in_value ? "in" : "",
                        field->out_value ? "out" : "",
                        i,
                        cmd->cmd.scan->num_fields,
                        field->num_bits);

                if (i == cmd->cmd.scan->num_fields - 1 && tap_get_state() != tap_get_end_state()) {
                        DEBUG_JTAG_IO("Last field and have to move out of SHIFT state");
                        /* Last field, and we're leaving IRSHIFT/DRSHIFT. Clock last bit during tap
                         * movement. This last field can't have length zero, it was checked above. */
                        cmsis_dap_add_jtag_sequence(
                                field->num_bits - 1, /* number of bits to clock */
                                field->out_value, /* output sequence */
                                0, /* output offset */
                                false, /* TMS low */
                                field->in_value,
                                0);

                        /* Clock the last bit out, with TMS high */
                        uint8_t last_bit = 0;
                        if (field->out_value)
                                bit_copy(&last_bit, 0, field->out_value, field->num_bits - 1, 1);
                        cmsis_dap_add_jtag_sequence(
                                1,
                                &last_bit,
                                0,
                                true,
                                field->in_value,
                                field->num_bits - 1);
                        tap_set_state(tap_state_transition(tap_get_state(), 1));

                        /* Now clock one more cycle, with TMS low, to get us into a PAUSE state */
                        cmsis_dap_add_jtag_sequence(
                                1,
                                &last_bit,
                                0,
                                false,
                                NULL,
                                0);
                        tap_set_state(tap_state_transition(tap_get_state(), 0));
                } else {
                        DEBUG_JTAG_IO("Internal field, staying in SHIFT state afterwards");
                        /* Clocking part of a sequence into DR or IR with TMS=0,
                           leaving TMS=0 at the end so we can continue later */
                        cmsis_dap_add_jtag_sequence(
                                field->num_bits,
                                field->out_value,
                                0,
                                false,
                                field->in_value,
                                0);
                }
        }

        if (tap_get_state() != tap_get_end_state()) {
                cmsis_dap_end_state(tap_get_end_state());
                cmsis_dap_state_move();
        }

        DEBUG_JTAG_IO("%s scan, %i bits, end in %s",
                (cmd->cmd.scan->ir_scan) ? "IR" : "DR", scan_size,
                tap_state_name(tap_get_end_state()));
}

static void cmsis_dap_pathmove(int num_states, tap_state_t *path)
{
        int i;
        uint8_t tms0 = 0x00;
        uint8_t tms1 = 0xff;

        for (i = 0; i < num_states; i++) {
                if (path[i] == tap_state_transition(tap_get_state(), false))
                        cmsis_dap_add_tms_sequence(&tms0, 1);
                else if (path[i] == tap_state_transition(tap_get_state(), true))
                        cmsis_dap_add_tms_sequence(&tms1, 1);
                else {
                        LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition.",
                                  tap_state_name(tap_get_state()), tap_state_name(path[i]));
                        exit(-1);
                }

                tap_set_state(path[i]);
        }

        cmsis_dap_end_state(tap_get_state());
}

static void cmsis_dap_execute_pathmove(struct jtag_command *cmd)
{
        DEBUG_JTAG_IO("pathmove: %i states, end in %i",
                      cmd->cmd.pathmove->num_states,
               cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]);

        cmsis_dap_pathmove(cmd->cmd.pathmove->num_states, cmd->cmd.pathmove->path);
}

static void cmsis_dap_stableclocks(int num_cycles)
{
        int i;

        uint8_t tms = tap_get_state() == TAP_RESET;
        /* TODO: Perform optimizations? */
        /* Execute num_cycles. */
        for (i = 0; i < num_cycles; i++)
                cmsis_dap_add_tms_sequence(&tms, 1);
}

static void cmsis_dap_runtest(int num_cycles)
{
        tap_state_t saved_end_state = tap_get_end_state();

        /* Only do a state_move when we're not already in IDLE. */
        if (tap_get_state() != TAP_IDLE) {
                cmsis_dap_end_state(TAP_IDLE);
                cmsis_dap_state_move();
        }
        cmsis_dap_stableclocks(num_cycles);

        /* Finish in end_state. */
        cmsis_dap_end_state(saved_end_state);

        if (tap_get_state() != tap_get_end_state())
                cmsis_dap_state_move();
}

static void cmsis_dap_execute_runtest(struct jtag_command *cmd)
{
        DEBUG_JTAG_IO("runtest %i cycles, end in %i", cmd->cmd.runtest->num_cycles,
                      cmd->cmd.runtest->end_state);

        cmsis_dap_end_state(cmd->cmd.runtest->end_state);
        cmsis_dap_runtest(cmd->cmd.runtest->num_cycles);
}

static void cmsis_dap_execute_stableclocks(struct jtag_command *cmd)
{
        DEBUG_JTAG_IO("stableclocks %i cycles", cmd->cmd.runtest->num_cycles);
        cmsis_dap_stableclocks(cmd->cmd.runtest->num_cycles);
}

static void cmsis_dap_execute_tms(struct jtag_command *cmd)
{
        DEBUG_JTAG_IO("TMS: %d bits", cmd->cmd.tms->num_bits);
        cmsis_dap_cmd_DAP_SWJ_Sequence(cmd->cmd.tms->num_bits, cmd->cmd.tms->bits);
}

/* TODO: Is there need to call cmsis_dap_flush() for the JTAG_PATHMOVE,
 * JTAG_RUNTEST, JTAG_STABLECLOCKS? */
static void cmsis_dap_execute_command(struct jtag_command *cmd)
{
        switch (cmd->type) {
                case JTAG_RESET:
                        cmsis_dap_flush();
                        cmsis_dap_execute_reset(cmd);
                        break;
                case JTAG_SLEEP:
                        cmsis_dap_flush();
                        cmsis_dap_execute_sleep(cmd);
                        break;
                case JTAG_TLR_RESET:
                        cmsis_dap_flush();
                        cmsis_dap_execute_tlr_reset(cmd);
                        break;
                case JTAG_SCAN:
                        cmsis_dap_execute_scan(cmd);
                        break;
                case JTAG_PATHMOVE:
                        cmsis_dap_execute_pathmove(cmd);
                        break;
                case JTAG_RUNTEST:
                        cmsis_dap_execute_runtest(cmd);
                        break;
                case JTAG_STABLECLOCKS:
                        cmsis_dap_execute_stableclocks(cmd);
                        break;
                case JTAG_TMS:
                        cmsis_dap_execute_tms(cmd);
                        break;
                default:
                        LOG_ERROR("BUG: unknown JTAG command type 0x%X encountered", cmd->type);
                        exit(-1);
        }
}

static int cmsis_dap_execute_queue(void)
{
        struct jtag_command *cmd = jtag_command_queue;

        while (cmd != NULL) {
                cmsis_dap_execute_command(cmd);
                cmd = cmd->next;
        }

        cmsis_dap_flush();

        return ERROR_OK;
}

static int cmsis_dap_speed(int speed)
{
        if (speed > DAP_MAX_CLOCK)
                LOG_INFO("High speed (adapter_khz %d) may be limited by adapter firmware.", speed);

        if (speed == 0) {
                LOG_ERROR("RTCK not supported. Set nonzero adapter_khz.");
                return ERROR_JTAG_NOT_IMPLEMENTED;
        }

        return cmsis_dap_cmd_DAP_SWJ_Clock(speed);
}

static int cmsis_dap_speed_div(int speed, int *khz)
{
        *khz = speed;
        return ERROR_OK;
}

static int cmsis_dap_khz(int khz, int *jtag_speed)
{
        *jtag_speed = khz;
        return ERROR_OK;
}

static int_least32_t cmsis_dap_swd_frequency(int_least32_t hz)
{
        if (hz > 0)
                cmsis_dap_speed(hz / 1000);

        return hz;
}


COMMAND_HANDLER(cmsis_dap_handle_info_command)
{
        if (cmsis_dap_get_version_info() == ERROR_OK)
                cmsis_dap_get_status();

        return ERROR_OK;
}

COMMAND_HANDLER(cmsis_dap_handle_cmd_command)
{
        int retval;
        unsigned i;
        uint8_t *buffer = cmsis_dap_handle->packet_buffer;

        buffer[0] = 0;  /* report number */

        for (i = 0; i < CMD_ARGC; i++)
                buffer[i + 1] = strtoul(CMD_ARGV[i], NULL, 16);

        retval = cmsis_dap_usb_xfer(cmsis_dap_handle, CMD_ARGC + 1);

        if (retval != ERROR_OK) {
                LOG_ERROR("CMSIS-DAP command failed.");
                return ERROR_JTAG_DEVICE_ERROR;
        }

        LOG_INFO("Returned data %02" PRIx8 " %02" PRIx8 " %02" PRIx8 " %02" PRIx8,
                buffer[1], buffer[2], buffer[3], buffer[4]);

        return ERROR_OK;
}

COMMAND_HANDLER(cmsis_dap_handle_vid_pid_command)
{
        if (CMD_ARGC > MAX_USB_IDS * 2) {
                LOG_WARNING("ignoring extra IDs in cmsis_dap_vid_pid "
                        "(maximum is %d pairs)", MAX_USB_IDS);
                CMD_ARGC = MAX_USB_IDS * 2;
        }
        if (CMD_ARGC < 2 || (CMD_ARGC & 1)) {
                LOG_WARNING("incomplete cmsis_dap_vid_pid configuration directive");
                if (CMD_ARGC < 2)
                        return ERROR_COMMAND_SYNTAX_ERROR;
                /* remove the incomplete trailing id */
                CMD_ARGC -= 1;
        }

        unsigned i;
        for (i = 0; i < CMD_ARGC; i += 2) {
                COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i], cmsis_dap_vid[i >> 1]);
                COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i + 1], cmsis_dap_pid[i >> 1]);
        }

        /*
         * Explicitly terminate, in case there are multiples instances of
         * cmsis_dap_vid_pid.
         */
        cmsis_dap_vid[i >> 1] = cmsis_dap_pid[i >> 1] = 0;

        return ERROR_OK;
}

COMMAND_HANDLER(cmsis_dap_handle_serial_command)
{
        if (CMD_ARGC == 1) {
                size_t len = mbstowcs(NULL, CMD_ARGV[0], 0);
                cmsis_dap_serial = calloc(len + 1, sizeof(wchar_t));
                if (cmsis_dap_serial == NULL) {
                        LOG_ERROR("unable to allocate memory");
                        return ERROR_OK;
                }
                if (mbstowcs(cmsis_dap_serial, CMD_ARGV[0], len + 1) == (size_t)-1) {
                        free(cmsis_dap_serial);
                        cmsis_dap_serial = NULL;
                        LOG_ERROR("unable to convert serial");
                }
        } else {
                LOG_ERROR("expected exactly one argument to cmsis_dap_serial <serial-number>");
        }

        return ERROR_OK;
}

static const struct command_registration cmsis_dap_subcommand_handlers[] = {
        {
                .name = "info",
                .handler = &cmsis_dap_handle_info_command,
                .mode = COMMAND_EXEC,
                .usage = "",
                .help = "show cmsis-dap info",
        },
        {
                .name = "cmd",
                .handler = &cmsis_dap_handle_cmd_command,
                .mode = COMMAND_EXEC,
                .usage = "",
                .help = "issue cmsis-dap command",
        },
        COMMAND_REGISTRATION_DONE
};

static const struct command_registration cmsis_dap_command_handlers[] = {
        {
                .name = "cmsis-dap",
                .mode = COMMAND_ANY,
                .help = "perform CMSIS-DAP management",
                .usage = "<cmd>",
                .chain = cmsis_dap_subcommand_handlers,
        },
        {
                .name = "cmsis_dap_vid_pid",
                .handler = &cmsis_dap_handle_vid_pid_command,
                .mode = COMMAND_CONFIG,
                .help = "the vendor ID and product ID of the CMSIS-DAP device",
                .usage = "(vid pid)* ",
        },
        {
                .name = "cmsis_dap_serial",
                .handler = &cmsis_dap_handle_serial_command,
                .mode = COMMAND_CONFIG,
                .help = "set the serial number of the adapter",
                .usage = "serial_string",
        },
        COMMAND_REGISTRATION_DONE
};

static const struct swd_driver cmsis_dap_swd_driver = {
        .init = cmsis_dap_swd_init,
        .frequency = cmsis_dap_swd_frequency,
        .switch_seq = cmsis_dap_swd_switch_seq,
        .read_reg = cmsis_dap_swd_read_reg,
        .write_reg = cmsis_dap_swd_write_reg,
        .run = cmsis_dap_swd_run_queue,
};

static const char * const cmsis_dap_transport[] = { "swd", "jtag", NULL };

struct jtag_interface cmsis_dap_interface = {
        .name = "cmsis-dap",
        .supported = DEBUG_CAP_TMS_SEQ,
        .commands = cmsis_dap_command_handlers,
        .swd = &cmsis_dap_swd_driver,
        .transports = cmsis_dap_transport,

        .execute_queue = cmsis_dap_execute_queue,
        .speed = cmsis_dap_speed,
        .speed_div = cmsis_dap_speed_div,
        .khz = cmsis_dap_khz,
        .init = cmsis_dap_init,
        .quit = cmsis_dap_quit,
};